Process for producing aniline black and for preventing the weakening of the fibers



Patented Aug. 1, 1933 PROCESS FOR PRODUCING ANILINE BLACK AND FOR PREVENTING THE WEAKENING OF THE FIBERS Karl Schmidt, Munich-Gladbach, Germany Application December 31, 1927,

No Drawing.

REISSUED Serial No. 244,037, and in Germany July 8,

2 Claims.

My invention relates to a new and useful process, which is adapted to produce a very deep aniline black on the material and, at the same time prevent the weakening of the fibers.

The usual methods for producing aniline black employ a composition, containing three essential components:

1. An aniline salt, generally aniline hydrochloride or nitrate.

. 2. An oxidizing agent, generally sodium or potassium chlorate, and

3. YA catalyst, generally a salt of a heavy metal, such as iron, manganese, copper, vanadium, lead and the like (e. g. potassium ferrocyanide, copper sulphate).

When these components interact the known black dyeing of the fabric takes places with liberation of mineral acids, which readily destroy the textile material.

It has already been proposed to add to the aforementioned components the salt of a weaker organic acid in order to bind the mineral salt. However, only a very small quantity of such an addition can be used, because large quantities would be liable to prevent the production of aniline black. The protective action of small quantities of such additions is practically insignificant. The addition of large quantities of alkali salts is used in order to produce the so-called reserves. At the places at whch theseare imprinted the aniline black cannot be developed and the mate-' rial, therefore, remains white.

Furthermore, it is known, that the addition of certain aromatic amines to the three components above-mentioned acts in a favourable manner, inasmuch as a deeper black is obtained and aniline salt is economized. However, no preservation of the fibers is effected in this way; on the contrary, the fibers are impaired just as much as in the normal process.

The technical and economical advantages of my process are obtained by using, besides the three above-mentioned components of an aniline black composition, one or several organic catalysts amines as a fourth component and large quantities of protective-acting alkali-metal salts of weak, volatile or easily oxidizable acids con taining sulphur as a fifth component.

It may be emphasized that the new process is based upon the simultaneous employment of two catalysts, namely a metallic (e. g. potassium ferro-cyanide) and an organic catalyst (e. g. p-phenylene-diamine) and of the above mentioned protective salts in large quantities.

In practice it has been found to be advantageous to use a mixture containing an organic .catalyst and alkali metal salts of protecting acids in suitable proportions, this mixture being immediately introduced into the slop-pad bath of the aniline black, which always contains the above named three components. The novelty and surprising effect of the invention is therefore that the addition of large quantities of alkali salts of volatile organic acids containing sulphur,. which generally act as reserves, and consequently hinder the development of the aniline black, does not act thus it an organic catalyst (amine) is added and that this reaction takes place in presence of a heavy metal catalyst.

According to one form of carrying out my process, the following substances and quantities may be used:

12 parts of aniline hydrochloride, 1 part of hydrochloric acid (conc.), 1 part of copper sulphate, five parts of sodium chlorate, 6 parts of potassium thiocyanate and 2 parts of p-phenylene diamine.

As a further example of my process the following ingredients may be used.

12 parts of aniline hydrochloride, 9 parts of potassium ierrocyanide, 5 parts of sodium chlorate, 5 parts of ammonium sulphite, 2 parts of p-phenyl'ene diamine and 3 parts of tartaric acid.

The textile material which has been imprinted or slop-padded with these solutions is further treated in the usual, known manner, it being suspendedin a chamber forseveral hours in moist heat, or being steamed in a so-called oxidation steamer for the purpose of developing the black dye.

If it is necessary to use dyestufis which'are diflicult to fix under aniline black, e. g. vat dyes, owing tothe fact that the same are not sufficiently fixed by the short steaming process, then in my process the steaming can be carried out for a correspondingly longer period of .time, without the textile fibers being appreciably efiected- What'I claim is:

1. In the process of dyeing fibrous material with aniline black a single dye-bath comprising the combination with an aniline salt, an alkali metal chlorate and a salt of a heavy metal. of an organic catalyst consisting of phenylene diamine and a protectively acting alkali salt consisting of potassium thiocyanate, as and for the purposes set forth.

2. As a composition of matter for dyeing fibrous materials with aniline black for preventing weakening of the fiber and for the production of a deep black color which ,does not turn green, the combination of an organic catalyst consisting of phenylene .diamine, and a protective salt consisting of potassium thiocyanate, in the approximate ratio of 1: 3;

, KARL SCHMIDT. 

